Whenever an important molecular tool is developed, new discoveries follow. Fluorescent and luminescent proteins are prime examples of tools that have had an enormous impact on biology. However, molecular biology and biophysics lack similar molecules that allow direct interrogation of the great variety of cellular functional RNAs. This project aims to develop fluorogenic aptamers and ribozymes, RNAs that can be detected with high spatial and temporal resolution in live cells, as well as in vitro. These clonable modules will also find applications in structural biology, particularly in NMR, X-ray crystallography, and luminescence-based measurements. Our goal is to use in vitro selections to identify RNA modules that bind chelated lanthanides with high affinity and selectivity. In addition, we will develop new method for in vitro selection of multiple-turnover enzymes and use this method to identify fluorogenic multiple-turnover ribozymes. The technique will then be used to discover new fluorophores together with the enzymes that catalyze their synthesis and will thus significantly extend the range of experiments that in vitro selections can be applied to. All together, this project will significantly improve our ability to analyze RNAs in vitro and in vivo, and will create methods for de novo selection of highly efficient multiple-turnover enzymes. PUBLIC HEALTH RELEVANCE: Ribonucleic acids are involved in many fundamental processes in biological systems. This project will develop new tools for efficient analysis of RNAs in live tissues and provide a platform the analysis of fundamental biological processes involving cellular and viral RNAs.